This application is related to copending U.S. patent application Ser. No. 11/059,790 filed on Feb. 16, 2005 (pending), assigned to the common assignee.
A variety of electro-optic transceivers are known in the art. Such devices typically include an optical laser module that converts an electrical signal into a modulated light beam that is coupled to an optical fiber, and a receiver that receives an optical signal from an optical fiber and converts it into an electrical signal. Traditionally, the optical laser module includes a laser diode (LD) and other optic components and it focus or directs the light from the laser diode onto the optic fiber, which in turn, is connected to network transmission line. The laser module is typically packaged in a hermetically sealed package in order to protect the laser diode from harsh environmental conditions.
The laser diode is provided as semiconductor chip that is typically a few hundred microns wide and 100–500 microns thick. The package in which they are sealed is typically in the butterfly or coaxial form factors with several electrical leads coming out of the package. These electrical leads are typically soldered to the circuit board containing the amplifier/limiter.
The coaxial laser modules have seen some use in fiber optic telecommunication and CATV applications. Such modules typically use transistor outline (TO) packages and provide a relatively low cost solution in some markets. However, for applications where the laser consumes a relatively large amount of power or the laser is operated over a wide range of ambient temperatures, the laser diode and other optical components must be cooled in order to meet the requirements of an extremely narrow frequency spectrum and stable LD performance. External, forced air cooling has been the method of choice.
The use of internal cooling with TO packages has proven difficult due to the limited space within the TO header and the size of the active and passive components found therein. One previous effort in this regard involved the cooling of a converter module using very small custom thermo-electric coolers (TECs) and was limited to the cooling of only the active components (i.e., the LD) and not the passive components (i.e., lens and isolator). The cooling of only the active components has been found to result in unstable optical performance where a wide range of operating temperatures are involved.
In order to address these deficiencies in prior designs, a new style of coaxial cooled laser module based on an optimized thermal and mechanical design is described below under illustrated embodiments of the invention. This proposed cooled laser module uses a commercially available miniaturized TEC and integrates both the active and the passive optical components on a temperature controllable platform to provide a stable laser and optical performance.